The toxicity of pesticides and environmental contaminates and methods of antagonizing the toxicity of these substances in the newborn will be studied. Attempts will be made to discover chemicals which will activate the newborn mixed function oxidase system in a relatively short time to be of practical use in an acute clinical intoxication. Such an activating agent would rapidly turn on the newborn detoxification machinery to decrease the body burden of intoxicant and ultimately diminish toxicity. Studies of the teratogenic hazards of environmental toxicants and factors influencing the teratogenic response will continue. A basic understanding of events producing abnormal development will hopefully provide tools for prevention, diagnosis, and treatment of abnormal intrauterine growth and development. Factors modulating placental transfer of environmental toxicants will be studied. These studies will provide information on physico-chemical properties of chemicals that retard transport from mother to fetus. These data may foster molecular modification of chemical structure to eliminate teratogenic activity. A cholinergic system in the placenta appears to modulate transport of various substances from mother to fetus. Definition and characterization of the role of this system in the etiology of chemical-induced teratogenesis will be undertaken. Developmental toxicology must address the potential mutagenic hazards of chemicals as well as their teratogenic activity. A study of currently applied mutagenic tests is proposed. Pharmacological assessment of these tests is proposed to provide tools for a judicious decision on the role or applicability of mutagen tests in drug evaluation studies and environmental monitoring.